Wood patches are known for repairing defects, such as pitch pockets, in wooden components for doors and the like. To ensure a tight patch fit, the defect is commonly removed by routing to yield a slot in the wood panel somewhat smaller than the dimensions of the wood patch. Elongate patches with triangular cross-sections having a radius of curvature on one surface have been found to grip particularly well into correspondingly shaped slots. The wood patch is basted with adhesive, and pressed into the defect slot with the grain of the wood patch oriented with the grain of the wood panel. Thereafter, the patch area is sanded to yield a patch that closely blends with the surrounding wood of the door component.
In today's lumber industry, the increasing scarcity of high-quality old growth timber has resulted in an increased need for wood patch utilization. This arises because wood defects, such as pitch pockets, occur with greater frequency in the lumber available today. This increase in defects occurs even in lumber for use in high-quality wood products, particularly those which are stained rather than covered by painting.
Accordingly, it is important to produce wooden patches efficiently and cheaply. U.S. Pat. No. 4,949,767 to Murphy discloses an apparatus for manufacturing wood patches. The Murphy apparatus uses a rectangular piece of wood stock secured by a clamp, from which wood patches are cut by a combination of two cutters. The lower surfaces of the patch are cut by a double router bit that follows a sinusoidal cam surface extending longitudinally along the piece of wood stock. The double router bit has a vertical and an angled cutting edge that produce a pointed protrusion on the wood stock along the sinusoidal path. The patch cutting is completed by a blade which cuts the stock longitudinally to sever the protrusions at the bottom of the sinusoids. The resulting patches are somewhat "boat shaped" with curved or radiused ends and a triangular cross-section. With this approach, there is a significant amount of waste of wood patch stock material.
The length of the patches produced by the Murphy apparatus is varied by substituting cams with different periodic geometry. To produce wood patches of precise dimensions, the periodic geometry on the cams must be precisely machined. Since the Murphy cam surfaces are of a substantial length, having as many as 10 or more repetitions of the periodic geometry, the machining of the cam may be expensive.
Another wood patch cutting device uses a manually-operated generally half-moon shaped cutter. The half-moon cutter is moved vertically downwardly in a stamping action through a piece of wood patch stock resting on a cutting block of ultra high molecular weight plastic. The blades shear the wood to yield a wood patch. Such blades tend to become dulled after a few dozen cycles, causing the grain of the wood patch to be crushed.
A need exists for an improved method and apparatus for forming wood patches which overcomes these and other disadvantages of the prior art.